1. Field of the Invention
This invention relates to a capacitor system for a 12V vehicle, a 42V vehicle, an electric vehicle, or a hybrid powered vehicle, all designed to offer highly improved energy efficiency.
2. Description of the Related Art
As a conventional electric capacitor device for a vehicle, the 12V vehicle employs a lead battery while the hybrid powered vehicle employs a nickel metal hydride battery. The former with the lead battery discharges only when under about 100 percent state of charge, an engine is started or is being stopped with light-load, and the latter with the nickel metal hydride storage battery controls, under 20-80 percent state of charge, discharging, alternator charging, and recharging.
Among the conventional capacitor devices, lowering the state of charge of the lead storage battery generates large crystals of lead sulfate with low reversibility, which becomes a cause of increase in the internal resistance. Therefore, the conventional capacitor device is not suitable for a rechargeable system or is characterized in its extremely low durability even if it may be used for the rechargeable system.
All of the conventional capacitor devices have employed an aqueous solution type storage battery, wherein when the state of charge of the battery goes over 50 percent, a charging reaction and aqueous electrolysis of an electrode active substance simultaneously occur with a reintegration reaction of gaseous oxygen generated from a positive electrode, which lowers the charging efficiencies.
Aspects of the invention include a capacitor system for a vehicle with a power source discharging upon starting an engine, charging by an alternator, or recharging upon braking. The power source is a capacitor unit with several connected modules in which ion conductive materials are arranged between a pair of electrode structures with large surface area materials and an electric double layer is formed between the large surface area materials in the electrode structure and an electrolyte of the ion conductive materials, wherein charging and discharging are controlled for a state of charge of the capacitor unit with several connected modules to be within a predetermined range; and a minimum charge within the predetermined range is sufficient for the engine to start while a maximum charge within the predetermined range is within rated voltage of the capacitor unit with several connected modules.
Further aspects include a capacitor system for a vehicle as above, wherein if the state of charge of the capacitor unit with several connected modules becomes lower than a predetermined range, discharging other than for starting the engine is inhibited.
Further aspects include the capacitor system for a vehicle as above, wherein if a state of charge of the capacitor unit with several connected modules becomes higher than a predetermined range after conducting one recharging operation upon braking, any type of charging is inhibited; and if the state of charge of the capacitor unit with several connected modules becomes higher than the predetermined range after a predetermined number of recharging, alternator charging is inhibited and recharging only is conducted.
Further aspects include a capacitor system for a vehicle with a power source discharging upon starting an engine, charging by the alternator, or recharging upon braking. The power source is the capacitor unit with several connected modules in which ion conductive materials are arranged between a pair of electrode structures with large surface area materials and an electric double layer is formed between the large surface area materials in the electrode structure and an electrolyte of the ion conductive materials, wherein charging and discharging are controlled for a state of charge of the capacitor unit with several connected modules to be 50-99 percent provided that the state of charge of the capacitor unit with several connected modules at rated voltage is 100 percent.
Further aspects include the capacitor system for a vehicle as above, wherein if a state of charge of the capacitor unit with several connected modules becomes higher than 99 percent, any type of charging is inhibited; and if the state of charge of the capacitor unit with several connected modules is 90-99 percent, alternator charging is inhibited and recharging only is conducted.
Further aspects include the capacitor system for a vehicle as above, wherein the capacitor module with several connected cells is configured such that plural modules of electrical double layer capacitor cells are arranged in series. The respective bypass circuit is arranged between the modules; charging of one or more high-charged modules is interrupted by use of the bypass circuit; and state of charges of all modules are controlled to be equalized.
Further aspects include the capacitor system for a vehicle as above, wherein if irregularity in the state of charges among the modules becomes more than a predetermined range, charging of one or more high-charged modules is interrupted; and state of charges of all modules are controlled to be equalized.
Further aspects include the capacitor system for a vehicle as above, wherein a power terminal is extended from an electric double layer capacitor cell terminal and the power is directly driven therefrom.